But Ms Collins, whom Mr Bridges beat in the race to become leader of the party earlier this year, told The AM Show on Friday she wouldn't "second-guess" her leader.

Asked if Mr Bridges made a "misstep" in calling the health issue "embarrassing", she said no.

"Simon's got a lot more information on this than me, and I back him on this. I'm not going to go and second-guess people. It's very easy to second-guess, but I don't have that information and I'm absolutely backing him.

"He's been dealing with what is obviously a difficult situation. I don't know all the detail, and I don't want to pry into any of that."

Jami-Lee Ross.
Photo credit: Newshub.

If she was leading the party, Ms Collins wouldn't rule out using the same word.

"I don't know, because I don't have all the details Simon has. I really don't. I think it's a difficult situation and he's done his job."

There has been speculation Mr Ross was the one who leaked Mr Bridges' expenses in August, triggering a manhunt inside the National Party which is ongoing. Mr Bridges says he still doesn't know who the culprit is, but insists Mr Ross' leave isn't related.

"The question is about Simon Bridges' judgement and leadership in this matter. He's created a huge furore out of something that, if it was competently managed, would have blown over in a couple of days."

Mr Wood's comments echoed those of political commentator Trish Sherson, who told The AM Show on Thursday he should never have launched an inquiry into who leaked his expenses.

"Bridges handled it perfectly [on] day one. When those expenses were leaked he came out and said, 'Hey - I was doing my job.' It didn't seem to have anywhere to go, the story died pretty quickly, and then [came] the whole decision around going after who leaked it. That's just taken on a whole life of its own."